includes about four minutes of tracking, and the ship spent most of that time making a roughly 180-degree turn.

It remains unclear why the ship turned around shortly before it sank. The third mate, who has been arrested, was steering at the time of the accident, in a challenging area where she had not steered before, and the captain said he was not on the bridge at the time.

Authorities have not identified the third mate, though a colleague identified her as Park Han-gyeol. Senior prosecutor Ahn Song-don said Monday the third mate has told investigators why she made the turn, but he would not reveal her answer, and more investigation is needed to determine whether the answer is accurate.